Slip ring



June 21, 1949. A. Hooo ET AL 2,473,526

SLIP RING Filed Nov. 19, 1945 IINVENTOR. ARTHUR HOOD MORRIS SOBEL y EDGAR A.TERHUNE Patented June 21, 1949 UNITED STATES PATENT OFFICE SLIP RING Arthur Hood, West Long Branch, N. J., Morris Sobel, New York, N. Y., and Edgar A. Terhune,

Red Bank, N. J.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3'70 0. G. 757) 2 Claims.

The invention described herein may be manuiactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

The present invention relates to slip rings, and particularly to slip rings adapted to making continuous electrical circuit connections for rotating components of high frequency electrical apparatus, and the like.

In providing electrical connections for rotary components of electrical circuits, it is both desirable and necessary to maintain not only a fixed circuit length through a movable connection, but also a minimum or negligible variation in resistance. Furthermore, consideration must be given to the problem of maintaining a minimum capacity between several circuit connections where a plurality of such connections are necessary. In addition, a high degree of insulation and large creepage space must be provided in the event that moisture may be present during operation of the apparatus.

Slip ring devices are ordinarily built up of a number of insulating members joined together. Such composite construction invites loosening of the parts and also leaves joints where moisture may collect, thus affecting the electrical characteristics of the apparatus.

Accordingly, it is an object of this invention to provide an improved slip ring device for electrical rotating circuit components which may effectively provide the desirable operating characteristics hereinbefore referred to and which at the same time is of simple construction and easily manufactured at low cost.

It is a further object to provide a slip ring device which has direct leads from the contact rings to the rotating electrical component.

It is also an object to provide a slip ring device for a plurality of rotating electrical circuit connections for high frequency radio, or similar apparatus, wherein a single body of ceramic insulating material may be provided with a plurality of closely spaced slip rings and multiple brush connections therefor in a relatively small space.

It is another object to provide a slip ring device which has a single unitary insulating body member of ceramic material, so as to eliminate some of the drawbacks of conventional composite body members.

In accordance with the invention, a plurality of flexible metallic conductors, respectively, are positioned in and sweated to the surface of a like plurality of previously metallized peripheral channels encircling a. unitary ceramic insulating ring, the ends of said conductors being threaded through holes on the inside of the ring directly to terminals mounted on one end thereof. Each flexible conductor is then surrounded by a metal slip ring, which is sweated thereto and into the said channels. A double arm spring contact element or brush is provided for each contact ring, said brushes being mounted on a ceramic insulated post similarly channeled to conform to the channels in the ceramic ring. There is thus produced a unitary slip ring which has no loose parts, no joints where moisture may collect, and which provides straight through electrical leads.

In the drawings,

Figure l is an elevational view of a multiple slip ring device embodying the present invention, installed upon the shaft of a rotary high frequency apparatus;

Figure 2 is a plan view of the device of Figure 1;

Figure 3 is an enlarged vertical sectional view, taken along the line 33 of Figure 2;

Figure 4 is a view similar to Figure 3; taken along the line 44 of Figure 2, showing only the ceramic insulating body; and,

Figure 5 is a plan view of Figure 3, partly sectioned along the line 5-5 of Figure 3.

Referring now more particularly to the drawings, the illustrated embodiment of the present invention comprises a one-piece annular insulating body ll of ceramic material. The outer periphery of said body II is provided with four relatively deep ring channels [3, the base surface of each of which channels is fiat, but has a semicircular groove H3 at its center. Each groove I5 is provided with a dog-legged terminal hole H which extends inwardly and then upwardly from one point of the groove.

A length of flexible, stranded wire 19 is positioned in each of the semicircular grooves l5 so as to extend in a circle completely around the body I I, and the two ends thereof extend through the corresponding terminal hole [I leading from said groove IS. A tubular metal terminal eyelet 2|, disposed at the upper end of the body ll, extends down into each of said terminal holes ll and surrounds the two ends of the wire l9 disposed therein. Each of said terminal holes [7 is also filled with solder 23 which securely retains the said ends in place.

Encircling each of said circles of flexible Wire [9, and in contact therewith, and secured in the channel I3, is a metal contact ring 25 which has a butt joint 21 at one point of its periphery. The body H is also provided with several vertical mounting holes 28.

The device just described may be secured to a rotating electrical component (not shown) in any suitable manner. As shown in the drawings (Figures 1 and 2), it is secured to a clamping collar 29 by means of several bolts 3| which extend down through the mounting holes 28 and are threaded into said clamping collar 29. The clamping collar 29 comprises a Washer-like flange 33 secured to the upper end of a split sleeve 35. The said sleeve 35 is provided with two apertured ears 3! adjustably spaced by the bolt 39, by means of which the device is secured to a coaxially positioned rotating shaft 4| which is secured to the rotating electrical component (not shown).

Positioned a little to one side of the split ring device .just described, and with its axis parallel thereto is a brush post 43, also ofceramlc material, which is generally cylindrical in shape and is also provided with a like plurality of brush channels 45 which completely encircle it. Said brush post 4: is secured to a fixed support 41 by means of a bolt 49 extending axially through the brush post 43.

To allow for expansion of the body l and brush post 83, the bolts 3| and 49 are preferably provided with washers 51 of resilient material, such as rubber.

Interposed between the several ring channels 13 in the body I l and the correlative brush channels 45 in the brush post 43 are a like plurality of brushes 53, each of which is made up of a strip of sprihg'y metal of the same width as the contact rings 25 and is in the general shape of the letter M, the central portion 54 being semicircular and of substantially the same radius as the brush channels 45, and the arms 56 are outwardly curved toward their extremities. Each brush 53 is provided with a suitable binding post 55. Each brush 53 is sprung into position so that its central circular portion 54 fits into one of the brush channels 45 and its two arms 56 make good electrical line contact at two positions on the corresponding contact ring 25.

In manufacturing the slip ring device just described, the procedure is as follows: The ceramic slip ring body H is first machined so as to cut the channels l3 and grooves 15, and to drill the terminal holes I! and the mounting holes 28. The body I l is then ceramically glazed and fired. A silver compound, containing elements of ceramic, is then painted into each channel I3 and groove and the body H is refired, thereby metallizing the said painted surfaces.

A single turn of stranded flexible wire I9 is then positioned in each groove I 5, the two ends thereof being threaded through the correlative terminal hole 11 and terminal eyelet 2|. The two ends of each wire 19 are then held taut while solder 23 is flowed down into said terminal hole H to secure them therein. The ends of the wires 19, extending beyond the eyelets 21 may then be cut off flush, but the better procedure is to leave them extending some distance so that they may later be directly mechanically joined to the leads (not shown) from the rotating electrical component aforementioned.

A plurality of ribbons of springy metal, such as phosphor bronze, the width of the channels 13, are then formed into contact slip rings to tightly fit over the circlesof wire I9, so that, when in place, the ends of said rings 25 form butt joints 21. In forming said rings they should preferably be bent into a circle of smaller radius than that of the wires [9, so that they will snugly grip said wires when they are sprung into place.

The stranded wires l9, the channels 13 and the inside surfaces of the contact rings 25 are then well tinned. The rings 25 are placed, respectively, into the channels 13 and an even pressure and high temperature is applied to said rings 25 while the body I l is turned through three hundred and sixty degrees. This operation sweats the contact rings 25, respectively, to the stranded wires l9 and the metalized surfaces of the channels 13, thereby forming a hard surfaced, continuous band. The outer surfaces of the contact rings 25 are then machined, polished and silver plated.

The device aforesaid allows the body II to be rotated with the shaft 41 and the electrical component attached to it, with continuous electrical contacts between said component and the stationary parts of the circuit.

While ther has been described what is at present considered a preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein Without departing from the invention, and it is therefore aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a slip ring device a one-piece annular ceramic body having a metallized channel extending completely about it, said channel having a substantially flat bottom surface except for a groove for receiving a conductor, a terminal hole extending from said groove through the body, a turn of a conductor positioned in said groove and having its ends threaded through the terminal hole, solder completely filling said terminal hole and surrounding said ends, a contact ring split at one point extending about said conductor in said channel, the conductor and ring being sweated to the metallized groove and channel and to each other to form a smooth, continuous contact surface about said body.

2. The slip ring device as set forth in claim 1 including a ceramic brush post having a brush channel spaced from and opposing one section of the contact ring, a brush of springy metal shaped substantially like the letter M so as to have a central portion and two springy arms, the central portion being shaped to partly encircle the brush channel and the two arms making springy contact against two portions of the contact ring.

ARTHUR HOOD. MORRIS SOBEL. EDGAR A. TERHUNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,255,248 Toll Feb. 5, 1918 1,366,552 Blackburn Jan. 25, 1921 1,393,564 Mills Oct. 11, 1921 1,407,776 Stone Feb. 28, 1922 1,480,656 Blackburn Jan. 15, 1924 1,566,220 Lilly r. Dec. 15, 1925 2,291,070 Bruno July 28, 1942 2,348,919 Milton May 16, 1944 

